How come in Sims Life Stories they only allow me to have two kids?

Hi. Ok. Well, right now I have a toddler and a child, I want a total of four kids in this game. So when they are both in bed they only have the option to woo hoo and make out and hug and stuff, but not try for a child like it was before. I thought that you could have like 8 kids. not 2!! I want to hurry up too, because my sims become elders in 8 days. And i tried adoption. but they said that we have too many youngsters!? can someone help me and tell me why this is?